One-piece plastic desk or table top files or trays have achieved a significant amount of commercial success in the last several years because of their relatively low cost, space saving advantages and ease of use. One such product takes the form of a stackable tray horizontal file wherein each tray has integral top, bottom, rear and side walls.
These files or stands are injection moldings and because of their size require a very large mold and an injection molding machine large enough to inject the full volume of resin to complete the entire product. Such tooling is extremely costly because of its size and many small to medium size injection molding machines cannot be used to manufacture this product.
While these one-piece prior plastic files, even though in some cases multiple pieces when stacked, are relatively inexpensive, their product shipping containers are very large and therefore the shipping cost per part is inordinately high for a product in this low price category. A still further problem is that, as in all plastic parts, there are molding defects that result from shrinkage, inadequate injection pressure and other causes that produce part rejects, and since these products are made in one piece, a defect in part of the product requires that the entire product be rejected, further increasing product cost.
Although there are several stackable horizontal trays commercially produced, the only ones that stack and lock require additional parts to effect locking and those that do not lock frequently are unstable when stacked to a certain height.
All of these characteristics of prior desk top plastic files or trays contribute to the cost and desirability of the product and it is a primary objective of the present invention to ameliorate these cost-producing features without sacrificing any product utility.